Speed changing mechanism

ABSTRACT

A speed changing mechanism having a rotary or linear motion and comprising a component provided with a recessed track made up of a number of sections, each including a recess, which are all of one shape and are joined together end-to-end; a component provided with a cam track; and an array of rolling body units, each of which is linearly movable and comprises two rollers arranged respectively in constant contact with the recessed track and the cam track in operation, the number of units being different to the number of recesses. At least one rolling body unit is connected to a piston/cylinder unit. Fluid pressure is either delivered to the unit to move the rolling body unit (s) linearly and drive the mechanism, or the piston/cylinder unit is used to transmit fluid pressure produced by linear movement of the rolling body unit when the mechanism is driven from an external power source.

United States Patent [191 Leeson SPEED CHANGING MECHANISM [76] Inventor: Patrick George Leeson, Charnwood,

27 Swithland Ln., Rothley, Leicestershire, England [22] Filed: July 26, 1971 [21] Appl. No.: 165,903

[30] Foreign Application Priority Data [451 Oct. 16, 1973 Primary Examiner-Charles J. Myhre Assistant Examiner-Wesley S. Ratliff, Jr. Attorney-Larson, Taylor & Hinds [57] ABSTRACT A speed changing mechanism having a rotary or linear motion and comprising a component provided with a recessed track made up of a number of sections, each including a recess, which are all of one shape and are joined together end-to-end; a component provided with a cam track; and an array of rolling body units, each of which is linearly movable and comprises two rollers arranged respectively in constant contact with the recessed track and the cam track in operation, the number of units being different to the number of recesses. At least one rolling body unit is connected to a piston/cylinder unit. Fluid pressure is either delivered to the unit to move the rolling body unit (s) linearly and drive the mechanism, or the piston/cylinder unit is used to transmit fluid pressure produced by linear movement of the rolling body unit when the mechanism is driven from an external power source.

10 Claims, 4 Drawing Figures PATENTEBUBT 16 E173 SHEET 2 [IF 4 PATENTEDIJBI 16 1975 11765253 SHEET U, UF 4 1 SPEED CHANGING MECHANISM This invention relates to speed .changing mechanisms.

In particular, the invention is concerned with speed changing mechanisms of the kind comprising a cam track, a recessed track having an array of identical sections evenly spaced from one another and each including a recess, and an array of identical units each comprising one or more rolling bodies, which units are in constant contact with both the tracks and are movable relatively to one another, seriatim, into and out of driving engagement with the sections of the recessed track under the control of the cam track. Thus, such a mechanism has three basic components one formed with the cam track, one formed with the recessed track and one carrying the rolling body units arranged at equal spacings from one another and movable relatively to the components. A mechanism of this kind will herein after be referred to as a speed changing mechanism of the kind concerned. i

The invention has, in'fact, been devised primarily in connection with the speec changing mechanism forming the subject of U.S. Pat. No. 3,507,159. In this mechanism the shape of the recessed track consists of at least two portions defined by either at least two different general mathematical formulae or a general mathematical formula having at least one constant and the same mathematical formula having at least one different constant, the shape of the cam track'being a generation of the shape of the recessed track. It is to be understood that there is no limitation in this regard.

Speed changing mechanisms of the kind concerned can have either a rotary or a linear motiomThe rolling body units may be of various forms ranging from single bodies of spherical or cylindrical shape to groups each of two or more such bodies connected to move together. Usually, in operation, an external power source is arranged to produce relative movement between any two of the components and this results in the third com ponent being driven. g

It will be appreciated that in a mechanism of the kind concerned the rolling body units each move linearly in a direction at or substantially at right angles to the general planes containing the recessed and cam tracks, i.e. in a radial direction relatively to the common axis of the three components in a rotary mechanism or in a direction perpendicular to the linear motion produced in a linear mechanism.

The object of the present invention is to utilise this linear motion of the rolling body units in speed changing mechanisms of the kind concerned.

Broadly considered; the speed changing mechanism according to the invention is characterised in that at least one of the rolling body units has associated therewith means for either transmitting energy from an external source of power to the unit to cause it to perform its linearmovement whereby two or three of the components of the mechanism are driven, or for transmitting to external means energy produced by the linear movement of the unit caused by the movement of two or three of the components of which at least one is driven by an external source of power. 1

Thus, the idea is that in one alternative the energy input to the mechanism is applied to at least one of the rolling body units in contrast to one or two of the components as in known arrangements, and this arrangement enables the mechanism to provide two different power energy outputs. In the other alternative, wherein the energy input is applied to at least one of the components as in known arrangements, the existing linear movement of at least one of the rolling body units is harnessed to provide a further energy output in addition to that or those already provided by one or two of the components.

In implementing the invention, the said means associated with the rolling body unit concerned may comprise a piston/cylinder unit the piston of which is connected to the unit.

The invention also provides, according to one embodiment, an infinitely variable speed changing mechanism. Thus, in the second alternative mentioned above, means may be provided to restrict the said further energy output so as to impede the movement of the rolling body unit and thereby control the relationship between the speeds of movement of the components carrying the tracks.

When the restrictor is in its minimum restriction position, the mechanism will operate normally, providing a pre-determined speed relationship between the two components. As the restriction is varied the relationships will vary in proportion. If the energy flow is stopped completely, the linear movement of the rolling body units ceases and the three components of the mechanism must rotate together. Obviously, provision will have to be made to allow the component carryinG the rolllng body units to rotate.

In order thatthe invention may be more clearly understood and readily carried into practice, two embodiments of speed changing mechanisms according to the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a partial longitudinal sectional view of a speed changing mechanism according to one embodiment,

FIG. 2 is a transverse sectional view on line 11 ll of FIG. 1,

FIG. 3 is a view similar to FIG. 1 of the second embodiment, and

FIG. 3a is a view similar to FIG. 2 of an alternative embodiment.

The two embodiments illustrated in the drawings are rotary mechanisms, but it is to be understood that the principles of the invention can also be applied to linear mechanisms. I

The speed changing mechanism illustrated in FIG. 1 has an annular series of units each comprising two cylindrical rollers l, 1'- rotatably mounted by studs 2, 2" on a slide body 3 which is free to slide in a slot 4 formed in a fixed casing 5. At its end remote from the axis of the mechanism each slide body 3 is extended to form a piston rod to which a piston 6 is attached, this piston operating in a cylinder 7 incorporated in the casing S.

The rollers l are in contact with a recessed track 8 formed on a member 9, and the rollers l are in contact with a cam track 10 formed on a member 11 which is attached to a shaft 12 free to rotate in a bearing 13 held in the casing 5. The members 9 and 11 are free to rotate relative to each other on the interposed bearing 14 and the member 9 rotates within the bearing 15 affixed to the casing 5.

In one method of actuating the mechanism, hydraulic fluid is supplied to and exhausted from cylinder 7 through ports 7a, 7b from a conventional hydraulic pump (not shown) to cause the rolling body unit comprising the rollers 1 and 1' and the slide body 3 to move linearly in a radial direction. This causes the two members 9 and 11 to rotate at different speeds but in constant ratio one to another and to the number of strokes of the piston 6 in a given time. It will be appreciated that the energy supplied to the cylinder 7 may be produced by any appropriate means involving, for example, the use of hydraulic fluids under pressure, ignition of combustible gases or any other suitable energy source.

The speed relationships between members 9 and 11 depend on the number of lobes in the recessed and cam tracks of the respective members 9 and 11 and the number of units 1, 1, 3. For example if (as in the illustrated embodiment) there are one lobe on cam track 10, 12 lobes (and hence recesses) on recessed track 8 and l 1 units, the member 11 will rotate once for each stroke of the piston 6 whilst the member 9 will rotate in the opposite direction to the extent of one-twelth of a revolution.

Alternatively, if the number of units is increased to thirteen, the members 9 and 11 will rotate in opposite and reversed directions but with the same speed relationships relative to each other as before.

It will be appreciated that one or more of the rolling body units can be driven at will so that the input energy can be varied within the design parameters according to the numbers of cylinders incorporated in the mechanism limited only by the number of units provided.

The known method of supplying energy to a speed changing mechanism is to apply a rotating source of power to one of the three components provided with the cam track, the recessed track and the units respectively, i.e. one of the components 5, 9 and 11 in the embodiment shown. In this case, the same speed relationships obtain as referred to above. From the foregoing, however, it will be appreciated that each cylinder 7 and piston 6 can now be used as a pump since the piston is being driven, i.e. as a means of transmitting a part of the total energy input, the rest of this input necessarily being transmitted mechanically through the component which is not driven or fixed.

Thus, FIG. 1 shows two ways of putting the linear motion of the rolling body units to practical effect. It will be appreciated that the potential applications of this arrangement are extremely diverse and many have considerable commercial significance.

For example, and again with reference to FIG. 1, the mechanism can be used as a motor having two different rotary output speeds with input energy applied to the cylinder 7. Alternatively, the mechanism can be used to provide one rotary output of a reduced or increased speed and one hydraulic output with one rotary input applied to one or other of the members 9 and 11. The hydraulic output can be used, for example, for driving a hydraulic motor or for hydraulically braking the rotary mechanical output of the mechanism by restricting the outlet flow from the cylinder 7 and thus hindering the free action of the piston 6. Clearly a mechanical braking effect is also possible, without the use of friction shoes, purely by preventing the linear motion of th rolling body units.

In FIG. 1 the two members 9 and 11 are free to rotate but the casing is fixed. If all three components of a speed changing mechanism are arranged so as to be rotatable in relation one to another and the linear motion of the rolling body units is utilised, a considerable number of new industrial applications can be envisaged. which have significant commercial possibilities. For example, there is a need for a reasonably priced, infinitely variable, speed reducing mechanism capable of operating over a wide speed range. An inexpensive solution to this problem, utilising the novel principles already referred to, is illustrated in FIG. 3 wherein some like parts are designated by the same reference numerals.

Referring to FIG. 3, it can be seen that whilst the m!- ers 1 and 1 and the studs 2 and 2 are similar to the arrangement illustrated in FIG. 1, the extension to the slide body 3 is cylindrical and forms a combined plunger and piston 16 which extends towards the axis of the mechanism and reciprocates within a cylinder 17 formed in a cage 18. This cage rotates on a shaft 19 via a bearing 20. The shaft 19 is free to rotate within bearings 21 set in the casing 5. Similarly the other two members 23 and 24 are free to rotate, being mounted respectively on and within plain bearings 22 and ball bearings 22A set in the casing 5. Teeth 25 cut in the member 23 mesh with teeth on a spur wheel 26 which is part of the driven mechanism (not shown).

It will be appreciated that if the cage 18 is held fixed relative to the casing 5, and the shaft 19 is rotated, the mechanism will act as a speed reducing mechanism, the member 24 acting as the output member provided the hydraulic arrangement incorporated is inoperative. However, the shaft 19 has formed therein a cavity 28 which is closed by a plug shaft 27, so that oil can be drawn from a sump (not shown) via an oil channel 30 and holes 29 and 31 in the shaft 19 into the cylinder 17' by the action of the plunger 16' moving in a direction away from the axis of the mechanism.

The hydraulic fluid in the cylinder 17 is forced out as the plunger 16 moves towards the axis since the valvetiming of the mechanism is so arranged that a hole 33 in the shaft 19 is opposite the outlet from the cylinder 17, so that the fluid flows into a second chamber 34 within the shaft 19, through a plug 37 at the end of the chamber 34, via a conical aperture 35 and a hole 38 back into the sump. This flow can be restricted or entirely stopped by the action of the conical plug 36 which is rotatably connected through a thrust washer 41 to a yoke 42. An actuating lever 44 is rotatably fixed to the casing 5 by a pivot and lug 43 and to the yoke 42 by a pin and slot 45. Thus, movement of the lever 44 causes the conical aperture 35 to be restricted or closed by the plug 36.

In operation of the mechanism, a rotating power source is coupled to the plug shaft 27. If the conical plug 36 is withdrawn completely giving no resistance to the free flow of the hydraulic fluid through the circuit described, the member 23 will rotate freely and no drive through member 24 to the spur wheel 26 can take place against the resistance of this spur wheel attached to the driven mechanism. If, however, the plug 36 is moved to restrict the flow through the aperture 35 by action of the lever 44, the free action of the slide body 3 and hence that of the entire rolling body unit will be impeded resulting in the member 24 rotating at a speed proportional to the degree of restriction of the fluid flow. If, by action of the lever 44, the fluid flow is stopped entirely the three components of the mechanism must rotate together so that the member 24 rotates at the same speed as the input shaft 19 and plug shaft 27 ignoring any possible hydraulic leaks.

Thus, an infinitely variable ratio between zero and input speed is achieved in a relatively simple and therefore cheap form of speed changing mechanism using the novel principles of the invention.

It will be appreciated that the timing arrangements of the parts permitting the fluid flow to and from the cyl-. inders 17, 17 can be implemented in a simple manner in the type of speed changing mechanism illustrated in FIG. 2. A groove cut on the outer periphery of the shaft 19 over 180 and a groove over the opposite 180 with appropriately spaced holes connecting the cylinders 17, 17' and the chamber 28 and 34 is all that is required.

Hitherto it does not seem to have been realised that speed changing mechanisms lend themselves to simple valve timing arrangements of the kind illustratd because the mechanical arrangement, once determined, ensures a fixed speed relationship between all three components of the mechanism and the number of linear radial strokes of the rolling body units as mentioned earlier. Y I

In more exacting, infinitely variable applications some further measures may need to be taken thereby adding to the sophistication of the arrangement shown in FIG. 2. For example, a known mechanically or hydraulically operated device may be needed to prevent slip at the top 1 1 ratio that can occur due to hydraulic losses. Further, it is evident in the intermediate speed range that the fluid will be heated by flowing through the restricted aperture 35 resulting in some degree of inefficiency due to loss of energy. This energy loss can be virtually eliminated by using the hydraulic fluid fed under pressure into the chamber 34 by action of the combined piston and plunger 16 to drive a motor which does useful work. If the motor is mounted on one of the components of the mechanism and so arranged that it will drive another one of the components, (e.g. components 24) in a manner already known in conventional epicyclic tooth-geared mechanisms, it can use the energy that would otherwise have been lost.

FIG. 3a shows the mechanism of FIG. 3 modified in accordance with this embodiment. In this case, fluid pumped along passageway 34 is delivered through porting P to a variable speed gear motor M which drives member 24 through a gear wheel G.

From the foregoing it will be appreciated that the use of the linear movement of the rolling body units in a speed changing mechanism in the novel manner described leads to a number of useful mechanical arrangements with considerable commercial potential.

I claim:

1. A speed changing mechanism of the kind comprising a first component formed with a cam track; a second component formed with a recessed track having an array of identical sections evenly spaced from one another and each including a recess; and a third component carrying an array of identical units each comprising one or more rolling bodies, which units are in constant contact with both the tracks and are movable relatively to one another, seriatim, into and out of driving engagement with the sections of the recessed track under the control of the cam track so as to control the relative speeds of said first and second components, said units being arranged at equal spacings from one another and linearly movable relatively to the components, said cam track and said recessed track being so formed as to provide for a speed differential between said first and second components, wherein the improvement comprises energy transmission means associated with at least one of said rolling body units, whereby energy delivered to said means from an external source of power can be transmitted to the unit to cause it to perform its linear movement whereby at least two of the components of the mechanism are driven, or energy produced by the linear movement of the unit caused by the movement of two or three of the components of which at least one is driven by an external source of power can be transmitted to external means.

2. A mechanism according to claim 1, wherein the said energy transmission means comprise a piston/cylinder unit, the piston of which is connected to the rolling body unit.

3. A mechanism according to claim 1 arranged to transmit energy produced by the linear movement of the unit, wherein means are provided to restrict the transmitted energy so as to impede the movement of the rolling body unit and thereby control the relationship between the speeds of movement of the components carrying the tracks.

4. A mechanism according to claim 1, wherein the recessed track and the cam track are arranged side by side so as to face in the same direction, each rolling body unit comprising two rolling bodies which engage the recessed track and the cam track respectively and are coupled together for movement in unison.

5. A mechanism according to claim 4, wherein the two rolling bodies in each unit are mounted on a slide body which is free to slide in the component carrying the rolling body units.

6. A mechanism according to claim 5, wherein the rolling bodies are cylindrical rollers.

7. A mechanism according to claim 1, which is of rotary form, wherein the cam track and recessed track are of annular form being arranged side by side with one surrounding the other.

8. A mechanism according to claim 7, wherein the components carrying the said tracks each have a cylindrical extension, the extensions being rotatable relatively to one another and one extension being housed inside the other.

9. A mechanism according to claim 8, wherein it is housed in a casing arranged to form the said component carrying the rolling body units.

10. A mechanism according to claim 1 arranged to transmit energy produced by linear movement of at least one rolling body unit, wherein it further includes a motor which is arranged to be driven by this transmitted energy and is itself arranged to drive one of the components of the mechanism. 

1. A speed changing mechanism of the kind comprising a first component formed with a cam track; a second component formed with a recessed track having an array of identical sections evenly spaced from one another and each including a recess; and a third component carrying an array of identical units each comprising one or more rolling bodies, which units are in constant contact with both the tracks and are movable relatively to one another, seriatim, into and out of driving engagement with the sections of the recessed track under the control of the cam track so as to control the relative speeds of said first and second components, said units being arranged at equal spacings from one another and linearly movable relatively to the components, said cam track and said recessed track being so formed as to provide for a speed differential between said first and second components, wherein the improvement comprises energy transmission means associated with at least one of said rolling body units, whereby energy delivered to said means from an external source of power can be transmitted to the unit to cause it to perform its linear movement whereby at least two of the components of the mechanism are driven, or energy produced by the linear movement of the unit caused by the movement of two or three of the components of which at least one is driven by an external source of power can be transmitted to external means.
 2. A mechanism according to claim 1, wherein the said energy transmission means comprise a piston/cylinder unit, the piston of which is connected to the rolling body unit.
 3. A mechanism according to claim 1 arranged to transmit energy produced by the linear movement of the unit, wherein means are provided to restrict the transmitted energy so as to impede the movement of the rolling body unit and thereby control the relationship between the speeds of movement of the components carrying the tracks.
 4. A mechanism according to claim 1, wherein the recessed track and the cam track are arranged side by side so as to face in the same direction, each rolling body unit comprising two rolling bodies which engage the recessed track and the cam track respectively and are coupled together for movement in unison.
 5. A mechanism according to claim 4, wherein the two rolling bodies in each unit are mounted on a slide body which is free to slide in the component carrying the rolling body units.
 6. A mechanism according to claim 5, wherein the rolling bodies are cylindrical rollers.
 7. A mechanism according to claim 1, which is of rotary form, wherein the cam track and recessed track are of annular form being arranged side by side with one surrounding the other.
 8. A mechanism according to claim 7, wherein the components carrying the said tracks each have a cylindrical extension, the extensions being rotatable relatively to one another and one extension being housed inside the other.
 9. A mechanism according to claim 8, wherein it is housed in a casing arranged to form the said component carrying the rolling body units.
 10. A mechanism according to claim 1 arranged to transmit energy produced by linear movement of at least one rolling body unit, wherein it further includes a motor which is arranged to be driven by this transmitted energy and is itself arranged to drive one of the components of the mechanism. 